Low oxygen environment alters transcripts related to energy metabolism without altering the pluripotency core of bovine embryonic stem cells.

Stem cell pluripotency is shaped by culture microenvironment. Growth factors, cytokines, and oxygen tension are key regulators of self-renewal and pluripotency state. Here we evaluated the adaptation of bovine embryonic stem cells (bESC) derived on mouse embryonic fibroblasts (MEF) to feeder-free conditions and the effects of low oxygen (5% O2) on their molecular profile. Primed bESC established on MEF and 21% O2 (high oxygen) were adapted to 5% O2 (low oxygen) and to feeder-free conditions in vitronectin to generate four culture conditions: high and low O2 tension in MEF and feeder-free. Adaptation to feeder-free upregulated transcripts related to cell differentiation in bESC cultured in high compared to low oxygen. Transition of bESC on MEF from normoxia to 5% O2 did not alter cell morphology or growth. Interestingly, colony morphology was maintained when transitioning bESC from MEF into feeder-free in low oxygen. Furthermore, there were fewer transcriptomic changes in bESC grown on MEF compared to feeder-free in low compared to high oxygen. While low oxygen tension did not alter the pluripotency profile of bESC, it promoted transcriptional changes related to energetic metabolism and increased mitochondrial membrane potential. These findings emphasize the importance of oxygen tension for derivation, maintenance, and performance of ESC.